Filter



1964 R. w. MALMSTROM 3,

FILTER Filed Oct. 27, 1960 2 Sheets-Sheet 1 Fig.4:

INVENTOR. RICHARD MALMSTEOM United States Patent ()fiice 3,163,834Patented Dec. 29, 1964 3,163,834 FILTER Richard W. Malmstrom,Springfield, Mass, assignor, by mesne assignments, to Three RiversIndustries, Inc., Three Rivers, Mass, a corporation of MassachusettsFiled Oct. 27, 1960, Ser. No. 65,505 2 Claims. (Cl. 333-79) Thisinvention relates to a new and improved device for use in electricalcircuits and which embodies incremently distributed inductance andcapacitance.

An object of the invention is to provide a new and improved device ofthe type set forth which may be adapted for use in any of theapplications of an artificial line, such as in time delay or pulseforming circuits, and which may also be adapted for radio interferencesuppression to bypass or eliminate undesirable radio frequency voltagesand which has means for substantially increasing the attenuation of thedevice.

Another object is to provide a new and improved device of the type setforth which allows the obtaining of a more compact and less expensivebut more effective device.

Other objects and advantages of the invention will be apparent from thefollowing description taken in connection with the accompanying drawingsin which the preferred forms of the invention have been given by way ofillustration only.

Referring to the drawings:

FIG. 1 is a sectional view of a device embodying the invention;

FIG. 2 is a partially exploded view illustrating the form of deviceembodying the invention of FIG. 1;

FIG. 3 is an electrical schematic View of one form of the invention ofFIGS. '1 and 2;

FIG. 4 is an electrical schematic view generally similar of a modifiedform of the invention;

FIG. 5 is a schematic view of one form of the invention;

FIG. 6 is a side view of the form of the invention shown in FIG. 5;

FIG. 7 is a schematic view of another form of the invention; and

FIG. 8 is a side view of the form of the invention shown in FIG. 7.

Referring more particularly to the drawings wherein similar referencecharacters designate corresponding parts throughout, the invention, asshown in FIGS. 1 and 2 comprises a pair of elements or units 1 and 2 inopposed relation in container 3. Between the uni-ts is placed the cuppedspring washer 4 insulated from container 3. The adjacent insulatedterminals 5 are connected at 6 to each other to connect the elements orunits 1 and 2 in series relation which results in a double unit withsubstantially increased attenuation over a unit of the same length witha single winding because the unit becomes a pi iilter.

The units it and 2 are secured in opposed relation in container 3 bycrimping the edge 7 of the container over the periphery of cover 8 withthe leads 5? extending through the ends of the container and havingterminals 16 secured thereto.

The form of the invention of FIGS. 5 and 6 includes the insulatingstrips or layers 15 between which is positioned the layer 16 which is athrough conducting foil.

The layer '16 of conducting material may be formed of a conductive foil,such as aluminum, copper, silver or n aluminum foil, or this layer couldbe a metallized deposit or coating on insulating strip or layer 15 or aconducting foil with coating of insulating material could be employed.

The insulating strips 15 could be formed of condenser paper, polyesterfilm or other suitable insulation material.

The materials employed would depend largely on the use to be made of theproduct, as well as space and cost considerations.

In spaced relation and insulated from conducting foil 16 by insulatingstrips 15a are provided the grounded conducting strip -17.

The insulating layers 15 maybe of any suitable insulating material, forexample, the impregnated type papers such as now are employed for woundcondensers or the layer may be of films of plastic materials or otherdielectric materials, either alone as insulating layers or with magneticor :ferro-magnetic character or coating in which case the inductance ofthe conductive layers would be enhanced.

The grounded layer 17 extends beyond one edge of the conductive layer 16and also extends beyond the.

material are then rolled into coilform, as shown in FIG.

1, or otherwise rolled or folded so as to form a relatively simple andcompact device.

The rolled or folded devices are then positioned in opposed relation ina casing 3 which is preferably of conducting material, although thecasing or housing could be of non-conducting material by providingsuitable connections to the foils. The projection on grounded layer 17may be compressed, forced or bonded into contact with the conductiveends 22 of the container to form a ground connection or these ends ofthe devices might be covered with a coating of a conductive materialsuch as solder which could form the desired ground connection byengagement with or soldering to the housing or suitable groundconnections can be applied if the housing is or is not of conductivematerial.

In the form of FIGS. 7 and 8, the ferro-magnetic or magnetic layer 25 isformed directly on insulating layer 15 and extends throughout thewinding and the grounded foil 17 also extends throughout the winding andis insulated from conductive layer 2.7 by insulating layer 28.

The device of FIGS. 7 and 8 are rolled and placed in the container 3 ina manner similar to that previously shown and described.

The magnetic strips 20 and the magnetic coating 25 serve to increase thereactance of the device.

From the foregoing it will be seen that I have provided new and improvedmeans for obtaining all of the objects and advantages of the invention.

I claim:

1. In a device of the character described, a pair of oppositely disposedelements connected in series relation forming a pi filter, each of saidelements comprising a winding consisting of a through conducting layer,insulating material for insulating the turns of said winding from eachother, and a grounded layer extending beyond an end of said insulatingmaterial and being grounded substantially throughout its length, saidconducting layer being connected in a closed circuit by a pair ofterminals adjacent the opposite ends of said conducting layer, saidgrounded layer, and a plurality of spaced magnetic portions in spacedrelation upon said conducting layer for increasing the reactance of thedevice, each of said elements having one of its pair of terminalselectrically connected to one of the pair of terminals of the otherelement such as to connect said elements in said series relation.

2. In a device of the character described, a pair of 0ppositely disposedelements connected in series relation forming :1 pi filter, each of saidelements comprising a winding consisting of a through conducting layer,insulating material for insulating the turns of said Winding from eachother, and a grounded layer extending beyond an end of said insulatingmaterial and being grounded substantially throughout its length, saidconducting layer being connected in a closed circuit by a pair ofterminals adjacent the opposite ends of said conducting layer, saidterminals being isolated from each other by said conducting layer,saidconducting layer forming an inductance in the closed circuit inWhlCll it is connected and a distributed capacitance with said groundedlayer, and a magnetic layer formed directly on said insulating rnanectedto one of the terminals of the other of said elements such as to connectsaid elements in series relation.

References Cited by the Examiner UNITED STATES PATENTS HERMAN KARLSAALBACH, Primary Examiner;

terial for increasing the reactance of the device, each of 20 M T NExaminersaid elements having one of its terminals electrically con-

1. IN A DEVICE OF THE CHARACTER DESCRIBED, A PAIR OF OPPOSITELY DISPOSEDELEMENTS CONNECTED IN SERIES RELATION FORMING A PI FILTER, EACH OF SAIDELEMENTS COMPRISING A WINDING CONSISTING OF A THROUGH CONDUCTING LAYER,INSULATING MATERIAL FOR INSULATING THE TURNS OF SAID WINDING FROM EACHOTHER, AND A GROUNDED LAYER EXTENDING BEYOND AN END OF SAID INSULATINGMATERIAL AND BEING GROUNDED SUBSTANTIALLY THROUGHOUT ITS LENGTH, SAIDCONDUCTING LAYER BEING CONNECTED IN A CLOSED CIRCUIT BY A PAIR OFTERMINALS ADJACENT THE OPPOSITE ENDS OF SAID CONDUCTING LAYER, SAIDTERMINALS BEING ISOLATED FROM EACH OTHER, SAID CONDUCTING LAYER FORMINGAN INDUCTANCE IN THE CLOSED CIRCUIT IN WHICH IT IS CONNECTED AND ADISTRIBUTED CAPACITANCE WITH SAID GROUNDED LAYER, AND A PLURALITY OFSPACED MAGNETIC PORTIONS IN SPACED RELATION UPON SAID CONDUCTING LAYERFOR INCREASING THE REACTANCE OF THE DEVICE, EACH OF SAID ELEMENTS HAVINGONE OF ITS PAIR OF TERMINALS ELECTRICALLY CONNECTED TO ONE OF THE PAIROF TERMINALS OF THE OTHER ELEMENT SUCH AS TO CONNECT SAID ELEMENTS INSAID SERIES RELATION.